Dental enamel EPR dosimetry: comparative testing of the spectra processing methods for determination of radiation-induced signal amplitude.

The aim of this investigation is to find out the optimal algorithm for mathematical processing of the EPR spectra of irradiated tooth enamel for estimating the amplitude of the radiation-induced signal, which is used for determination of the absorbed dose in enamel for retrospective individual dosimetry. A recently developed analytical model, which takes into account the line shape variation of the enamel EPR spectral components registered at different microwave power, was applied to spectra processing in various operation modes to simulate spectra processing techniques differing by the number of fitted parameters. The precision of dose determination at spectra processing was assessed by the root mean square deviation between experimental and nominal doses for sets of spectra of enamel samples irradiated in different doses and measured at different microwave power. It is shown that in the case of pooled enamel samples prepared as a mixture from different teeth, the higher precision of spectra processing is obtained using a model with fixed native background signal line shape (characterized by width and asymmetry parameters). In case of individual samples prepared each from a different tooth, better results are obtained using a model with variable background signal line shape.